Organic light emitting display device

ABSTRACT

An organic light emitting display device comprises two emission portions between first and second electrodes, wherein at least one among the two emission portions includes two emitting layers, whereby efficiency and a color reproduction ratio may be improved.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/205,025, filed Nov. 29, 2018, which is a Divisional of U.S. patentapplication Ser. No. 14/873,414, filed Oct. 2, 2015, which claims thebenefit of the Korean Patent Application No. 10-2014-0182517, filed onDec. 17, 2014, all of which are hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an organic light emitting displaydevice, and more particularly, to an organic light emitting displaydevice that may improve efficiency and a color reproduction ratio.

Discussion of the Related Art

Recently, with the advancement of the information age, a display fieldfor visually displaying an electric information signal has been rapidlydeveloped. In response to this trend, various flat panel display deviceshaving excellent properties of a thin profile, a light weight, and lowpower consumption have been developed.

Detailed examples of the flat panel display devices include liquidcrystal display (LCD) devices, plasma display panel (PDP) devices, fieldemission display (FED) devices, and organic light emitting display(OLED) devices.

Particularly, the organic light emitting display device is a self lightemitting diode, and is more advantageous than the other flat paneldisplay devices in view of a fast response speed, high light emissionefficiency, high luminance and a broad viewing angle.

The organic light emitting diode is based on that an organic emittinglayer is formed between two electrodes, electrons and holes from the twoelectrodes are injected into the organic emitting layer to generate anexciton through combination of the electrons and the holes, and light isgenerated when the exciton is transited from the excited state to aground state.

Related Art Reference

[Patent Reference]

(Patent reference 1) 1. White organic light emitting diode (KoreanPatent Application No. 10-2009-0092596)

An organic light emitting diode emitting white light may have astructure of two emitting layers of which colors are complementary toeach other. This structure generates a difference between a wavelengtharea of an electroluminescence (EL) peak of each emitting layer and atransmissive area of a color filter when white light passes through thecolor filter. Therefore, a problem occurs in that it is difficult toobtain a desired color reproduction ratio as a color range, which may bedisplayed, becomes narrow.

For example, in case of an organic light emitting diode emitting whitelight, which includes a blue emitting layer and a white-green emittinglayer, an EL peak wavelength is formed in a blue wavelength area and ayellow-green wavelength area, whereby white light is emitted. However,transmittance of the blue wavelength area becomes lower thantransmittance of a red or green wavelength area when the white lightpasses through red, green and blue color filters, whereby emissionefficiency and a color reproduction ratio are lowered. Also, the blueemitting layer is formed of a fluorescent emitting material, and theyellow emitting layer is formed of a phosphorescence emitting material.Emission efficiency of the yellow phosphorescence emitting layer isrelatively higher than emission efficiency of the blue fluorescentemitting layer, whereby emission efficiency and the color reproductionratio are reduced due to a difference in efficiency between the yellowphosphorescence emitting layer and the blue fluorescent emitting layer.

Also, in case of a bottom emission type device, a polarizer should beused to lower reflectance of an external light source. A problem occursin that luminance is reduced in the range of 60 %, approximately, due tothe use of the polarizer.

In this respect, the inventors of the present invention have recognizedthe aforementioned problems and invented an organic light emittingdisplay device of a new structure, which may improve efficiency and acolor reproduction ratio.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an organic lightemitting display device that substantially obviates one or more problemsdue to limitations and disadvantages of the related art.

An object of the present invention is to provide an organic lightemitting display device that includes two emission portions, one amongtwo emission portions having two emitting layers, to improve efficiencyand a color reproduction ratio.

Additional advantages and features of the invention will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, anorganic light emitting display device comprises first and secondelectrodes facing each other on a substrate; a first emission portion onthe first electrode; and a second emission portion on the first emissionportion, wherein the first emission portion or the second emissionportion includes one among a green emitting layer and a yellow-greenemitting layer and a red emitting layer to improve any one among greenefficiency, red efficiency, and color shift rate property.

The first emission portion includes the green emitting layer and the redemitting layer.

The second emission portion includes a dark blue emitting layer.

The green emitting layer is closer to the first electrode than the redemitting layer.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 200 nm to 230 nm toimprove red efficiency.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 320 nm to 350 nm toimprove the color shift rate property.

The red emitting layer is closer to the first electrode than the greenemitting layer.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 200 nm to 230 nm toimprove green efficiency.

The second emission portion includes the green emitting layer and thered emitting layer.

The red emitting layer is closer to the second electrode than the greenemitting layer.

The first emission portion includes a dark blue emitting layer.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 320 nm to 350 nm toimprove green efficiency.

The first emission portion includes the yellow-green emitting layer andthe red emitting layer.

The second emission portion includes a blue emitting layer.

The yellow-green emitting layer is closer to the first electrode thanthe red emitting layer.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 200 nm to 240 nm toimprove red efficiency.

The organic light emitting display device further comprises organiclayers between the first electrode and the second electrode, wherein theorganic layers have a thickness in the range of 340 nm to 370 nm toimprove the color shift rate property.

Each of the first electrode and the second electrode includes one amongITO (indium tin oxide), IZO (indium zinc oxide), and IGZO (indiumgallium zinc oxide).

Each of the first electrode and the second electrode includes one amonga reflective electrode and a transflective electrode.

Each of the first emission portion and the second emission portionincludes electroluminescence (EL) peaks in the ranges of 440 nm to 480nm, 530 nm to 580 nm, and 600 nm to 650 nm.

In another aspect, an organic light emitting display device comprisesfirst and second electrodes facing each other on a substrate; a firstemission portion on the first electrode; and a second emission portionon the first emission portion, wherein at least one among the firstemission portion and the second emission portion includes two emittinglayers, and the first emission portion and the second emission portionhave emission characteristics that exhibit three EL peaks. The firstemission portion includes the two emitting layers, and the secondemission portion includes a single emitting layer.

The two emitting layers in the first emission portion include a greenemitting layer and a red emitting layer, and the single emitting layerin the second emission portion includes a dark blue emitting layer.

The two emitting layers in the first emission portion include ayellow-green emitting layer and a red emitting layer, and the singleemitting layer in the second emission portion includes a blue emittinglayer.

The first emission portion includes a single emitting layer, and thesecond emission portion includes two emitting layers.

The single emitting layer in the first emission portion includes a darkblue emitting layer, and the two emitting layers in the second emissionportion include a green emitting layer and a red emitting layer.

The three EL peaks have wavelengths in the ranges of 440 nm to 480 nm,530 nm to 580 nm, and 600 nm to 650 nm.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1A and 1B are diagrams illustrating a PL spectrum of an emittinglayer according to an example embodiment of the present invention;

FIG. 2 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a first example embodiment and a secondexample embodiment of the present invention;

FIG. 3 is a diagram illustrating a contour map according to the firstembodiment of the present invention;

FIG. 4 is a diagram illustrating a contour map according to the secondembodiment of the present invention;

FIG. 5 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a third example embodiment of the presentinvention;

FIG. 6 is a diagram illustrating a contour map according to the thirdembodiment of the present invention;

FIG. 7 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a fourth example embodiment of the presentinvention;

FIG. 8 is a diagram illustrating a contour map according to the fourthembodiment of the present invention;

FIG. 9 is a diagram illustrating EL spectrum according to the first tofourth embodiments of the present invention;

FIG. 10 is a diagram illustrating a color shift rate based on a viewingangle according to the first to fourth embodiments of the presentinvention;

FIG. 11 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to fifth and sixth example embodiments of thepresent invention;

FIG. 12 is a diagram illustrating a contour map according to the fifthembodiment of the present invention;

FIG. 13 is a diagram illustrating a contour map according to the sixthembodiment of the present invention;

FIG. 14 is a diagram illustrating EL spectrum according to the fifth andsixth embodiments of the present invention;

FIG. 15 is a diagram illustrating a color shift rate based on a viewingangle according to the fifth and sixth embodiments of the presentinvention; and

FIG. 16 is a cross-sectional diagram illustrating an organic lightemitting display device according to an example embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Advantages and features of the present invention, and implementationmethods thereof will be clarified through following embodimentsdescribed with reference to the accompanying drawings. The presentinvention may, however, be embodied in different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the present invention tothose skilled in the art. Further, the present invention is only definedby scopes of claims.

A shape, a size, a ratio, an angle, and a number disclosed in thedrawings for describing embodiments of the present invention are merelyan example, and thus, the present invention is not limited to theillustrated details. Like reference numerals refer to like elementsthroughout. In the following description, when the detailed descriptionof the relevant known function or configuration is determined tounnecessarily obscure the important point of the present invention, thedetailed description will be omitted. In a case where ‘comprise’,‘have’, and ‘include’ described in the present specification are used,another part may be added unless ‘only˜’ is used. The terms of asingular form may include plural forms unless referred to the contrary.

In construing an element, the element is construed as including an errorrange although there is no explicit description.

In description of embodiments of the present invention, when a structure(for example, an electrode, a line, a wiring, a layer, or a contact) isdescribed as being formed at an upper portion/lower portion of anotherstructure or on/under the other structure, this description should beconstrued as including a case where the structures contact each otherand moreover, a case where a third structure is disposed therebetween.

In describing a time relationship, for example, when the temporal orderis described as ‘after˜’, subsequent˜', ‘next˜’, and ‘before˜’, a casewhich is not continuous may be included unless ‘just’ or ‘direct’ isused.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement, without departing from the scope of the present invention.

Features of various embodiments of the present invention may bepartially or overall coupled to or combined with each other, and may bevariously inter-operated with each other and driven technically as thoseskilled in the art can sufficiently understand. The embodiments of thepresent invention may be carried out independently from each other, ormay be carried out together in co-dependent relationship.

Hereinafter, the embodiments of the present invention will be describedin detail with reference to the accompanying drawings.

Since an emitting layer constituting an organic light emitting diodeincludes at least one host and at least one dopant, the emitting layerwill be described with reference to FIG. 1 illustratingPhotoLumincescence (PL) spectrum of the emitting layer. In thisembodiment, a structure of an organic light emitting display deviceaccording to various embodiments is suggested in which luminance and anaperture ratio are improved using a top emission type and efficiency anda color reproduction ratio are improved.

In this case, an ElectroLuminescence (EL) peak of the organic lightemitting display device that includes the organic light emitting diodeis determined by the product of PhotoLumincescence (PL) peak displayinga unique color of an emitting layer and Emittance (EM) peak of organiclayers constituting the organic light emitting diode. The emittance (EM)peak of the organic layers is affected by thicknesses and opticalproperties of the organic layers.

FIGS. 1A and 1B are diagrams illustrating a PL spectrum of an emittinglayer, which constitutes an organic light emitting diode.

FIG. 1A illustrates a PL spectrum of a phosphorescence green dopant(marked with {circumflex over (1)}), a phosphorescence yellow-greendopant (marked with {circumflex over (2)}) and a phosphorescence reddopant (marked with {circumflex over (3)}).

FIG. 1B illustrates a PL spectrum of a deep blue dopant (marked with{circumflex over (4)}) and a blue dopant (marked with {circumflex over(5)}).

As already described, the organic light emitting diode emits light asexciton generated by recombination of holes and electrons emits energy.Electroluminescence for emitting light has two properties, that is,fluorescence and phosphorescence, wherein the fluorescence emits lightas the exciton is transited from a singlet level to an excited state,and the phosphorescence emits light as the exciton is transited from atriplet level to an excited state.

As shown in FIG. 1A, a phosphorescence green dopant {circumflex over(4)} of which maximum wavelength of a PL peak is 532 nm is used, ayellow-green dopant {circumflex over (2)} of which maximum wavelength ofa PL peak is 556 nm is used, and a red dopant {circumflex over (3)} ofwhich maximum wavelength of a PL peak is 620 nm.

As shown in FIG. 1B, a deep blue dopant {circumflex over (4)} of whichmaximum wavelength of a PL peak is 444 nm is used, and a blue dopant{circumflex over (5)} of which maximum wavelength of a PL peak is 456 nmis used. Since the deep blue dopant {circumflex over (5)} is arranged ina wavelength area shorter than that of the blue dopant {circumflex over(5)}, it may be favorable for improvement of a color reproduction ratioand luminance.

Hereinafter, the organic light emitting diode of various embodiments towhich dopants described in FIGS. 1A and 1B are applied will bedescribed.

The present invention suggests an organic light emitting diode ofvarious embodiments, which includes two emission portions, at least oneamong having two emitting layers. The two emitting layers may includeone among a green emitting layer and a yellow-green emitting layer, anda red emitting layer.

FIG. 2 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a first example embodiment and a secondexample embodiment of the present invention.

The organic light emitting diode 100 shown in FIG. 2 includes first andsecond electrodes 102 and 104 on a substrate 101, and first and secondemission portions 110 and 120 between the first electrode 102 and thesecond electrode 104.

The first electrode 102 is a positive electrode for supplying holes, andmay be formed of, but is not limited to, Δu, Ag, Al, Mo, Mg, or theiralloy. Alternatively, the first electrode 102 may be formed of, but isnot limited to, ITO (indium tin oxide), IZO (indium zinc oxide), or IGZO(indium gallium zinc oxide). A reflective electrode may additionally beprovided below the first electrode 102 to reflect light toward thesecond electrode 104.

The second electrode 104 is a negative electrode for supplyingelectrons, and may be formed of, but is not limited to, ITO (indium tinoxide), IZO (indium zinc oxide), or IGZO (indium gallium zinc oxide),which is a transparent conductive material such as TCO (transparentconductive oxide). A buffer layer may additionally be provided below thesecond electrode 104 to prevent the second electrode 104 from beingdamaged by sputtering when the second electrode 104 is formed.

Alternatively, each of the first and second electrodes 102 and 104 maybe formed of, but is not limited to, one among ITO (indium tin oxide),IZO (indium zinc oxide), and IGZO (indium gallium zinc oxide).

The first electrode 102 may be referred to as anode and the secondelectrode 104 may be referred to as cathode.

A top emission type, in which the first electrode 102 is a reflectiveelectrode and the second electrode 104 is a transflective electrode,will be applied to the present invention.

In the first and second embodiments of the present invention, the firstemission portion includes two emitting layers, and the second emissionportion includes a single emitting layer. The two emitting layers in thefirst emission portion include a green emitting layer and a red emittinglayer, and the single emitting layer in the second emission portionincludes a deep blue emitting layer.

The first emission portion 110 may include a first hole transportinglayer (HTL) 112, a first emitting layer (EML) 114, a second emittinglayer (EML) 115, and a first electron transporting layer (ETL) 116.

The first emission portion 110 may further include a hole injectinglayer (HIL) above the first electrode 102. The hole injecting layer(HTL) is formed above the first electrode 102, and serves to activelyinject holes from the first electrode 102.

The first hole transporting layer (HTL) 112 supplies the holes from thehole injecting layer (HIL) to the first emitting layer (EML) 114 and thesecond emitting layer (EML) 115. The first electron transporting layer(ETL) 116 supplies electrons from the second electrode 104 to the firstemitting layer (EML) 114 and the second emitting layer (EML) 115 of thefirst emission portion 110.

The first hole transporting layer (HTL) 112 may include one or morelayers or one or more materials. The first hole transporting layer (HTL)112 may be formed of, but is not limited to, any one or more amongNPD(N,N-dinaphthyl-N,N′-diphenylbenzidine), TPD(N,N-diphenyl-N,N′-di(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine),Spiro-TAD(2,2′,7,7′-tetrakis(N,N-diphenlylamino)-9,9′-spirofluorene andMTDATA(4,4′,4″-tris(N-3-methylphenyl-N-phenylamino)tri phenylamine).

The hole injection layer (HIL) may be formed of, but is not limited to,MTDATA(4,4′,4″-tris(N-3-methylphenyl-N-phenylamino)triphenylamine),CuPc(phthalocyanine, copper complex) orPEDOT/PSS(poly(3,4-ethylenedioxythiphene/polystyrene sulfonate).

The holes supplied through the first hole transporting layer (HTL) 112and the electrons supplied through the first electron transporting layer(ETL) 116 are recombined with each other in the first emitting layer(EML) 114 and the second emitting layer (EML) 115, whereby light isgenerated.

The first electron transporting layer (ETL) 116 may include one or morelayers or one or more materials. The first electron transporting layer(ETL) 116 may be formed of, but is not limited to, any one or more amongAlq₃(tris(8-hydroxyquinolinato)aluminum),PBD(2-(4-biphenyl)5-(4-tert-butylphenyl)-1,3,4-oxadiazole),TAZ(3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole),Liq(8-hydroxyquinolinolato-lithium) andBAlq(Bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminum).

The first emitting layer (EML) 114 constituting the first emissionportion 110 includes a green emitting layer, and the second emittinglayer (EML) 115 includes a red emitting layer. The green emitting layermay be closer to the first electrode 102 than the red emitting layer.

The first emitting layer (EML) 114 of the first emission portion 110includes a green emitting layer to which a green dopant of which maximumwavelength of a PL peak is 532 nm is applied. And, the second emittinglayer (EML) 115 includes a red emitting layer to which a red dopant ofwhich maximum wavelength of a PL peak is 620 nm is applied.

The dopant in the first emitting layer (EML) 114 may be formed of, butis not limited to, Ir(ppy)3(Tris(2-phenylpyridine)iridium(III)). And,the dopant in the second emitting layer (EML) 115 may be formed of, butis not limited to, Ir(piq)3(Tris(1-phenylisoquinoline)iridium(III)),Ir(piq)2(acac)(Bis(1-phenylisoquinoline)(acetylacetonate)iridium(III)),Ir(btp)2(acac)(Bis)2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III)),orIr(BT)2(acac)(Bis(2-phenylbenzothazolato)(acetylacetonate)iridium(III)).

A charge generating layer (CGL) 140 may further be provided between thefirst emission portion 110 and the second emission portion 120. Thecharge generating layer (CGL) 140 controls charge balance between thefirst emission portion 110 and the second emission portion 120. Thecharge generating layer 140 may include an N type charge generatinglayer (N-CGL) and a P type charge generating layer (P-CGL). The N typecharge generating layer (N-CGL) serves to inject electrons to the firstemission portion 110, and the P type charge generating layer (P-CGL)serves to inject holes to the second emission portion 120. The chargegenerating layer (CGL) 140 may be formed of a single layer.

The second emission portion 120 may include a second hole transportinglayer (HTL) 122, a third emitting layer (EML) 124, and a second electrontransporting layer (ETL) 126.

The second emission portion 120 may further include an electroninjecting layer (EIL) above the second electron transporting layer (ETL)126. The electron injecting layer (EIL) is formed by doping an alkalimetal on the electron transporting layer (ETL). The alkali metal may beformed of, but is not limited to, Li, Na, Mg, or Ca. The electrontransporting layer (ETL) may be formed of, but is not limited to, afused aromatic ring based organic material, which includes aheterocyclic ring. The alkali metal may be doped in the range of 0.6% ormore and 2.0% or less.

The second emission portion 120 may further include a hole injectinglayer (HIL).

The second hole transporting layer (HTL) 122 may be formed of, but isnot limited to, the same material as that of the first hole transportinglayer (HTL) 112.

The second hole transporting layer (HTL) 122 may include, but is notlimited to, one or more layers or one or more materials.

The second electron transporting layer (ETL) 126 may be formed of, butis not limited to, the same material as that of the first electrontransporting layer (ETL) 116.

The second electron transporting layer (ETL) 126 may include one or morelayers or one or more materials.

The third emitting layer (EML) 124 of the second emission portion 120includes a dark blue emitting layer. The third emitting layer (EML) 124includes a dark blue emitting layer to which a dark blue dopant of whichmaximum wavelength of a PL peak is 444 nm is applied. The dopant in thethird emitting layer (EML) 124 may be formed of, but is not limited to,an iridium based material.

As previously described, the organic light emitting diode emits light asexciton generated by recombination of holes and electrons emits energy.Electroluminescence for emitting light has two properties, that is,fluorescence and phosphorescence, wherein the fluorescence emits lightas the exciton is transited from a singlet level to an excited state,and the phosphorescence emits light as the exciton is transited from atriplet level to an excited state. In this case, one exciton istransited in the singlet level while three excitons are transited in thetriplet level, whereby the fluorescence has efficiency of 25% and thephosphorescence has efficiency of 75%. Triplet-Triplet Annihilation(TTA) and delayed fluorescence should be used to improve internalquantum efficiency of the fluorescence type electroluminescence. The TTArepresents that collision occurs between triplet excitons having a longlifetime as the excitons are adjacent to each other at high density, andsome of the triplet excitons are transited to singlet excitons to emitlight. The triplet excitons are transited to the singlet excitons by theTTA to emit light, whereby internal quantum efficiency may be improved.For example, transition and collision of the singlet excitons, which arecaused by collision of the triplet excitons having a lifetime longerthan a lifetime of the singlet excitons directly excited, make delayedfluorescence. Electroluminescence efficiency may be more improved by thedelayed fluorescence.

Therefore, the TTA and delayed fluorescence are used to improveefficiency of the dark blue emitting layer which is the third emittinglayer (EML) 124 of the second emission portion 120. As the delayedfluorescence through the TTA contributes to electroluminescence based onthe singlet excitons, internal quantum efficiency (IQE) may be improvedfrom 25% to 40%. In order that the TTA efficiently occurs in theemitting layer, if an energy difference (singlet-triplet exchangeenergy; ΔEst) between a singlet level and a triplet level of a host anda dopant of the emitting layer becomes smaller, energy transition fromthe triplet to the singlet occurs easily. In order that the tripletexcitons are formed effectively in the emitting layer, a triplet energyof the hole transporting layer (HTL) and the electron transporting layer(ETL) should be higher than the triplet energy of the host of theemitting layer. That is, the triplet energy of the second holetransporting layer (HTL) 122 and the second electron transporting layer(ETL) 126 is adjusted to be higher than the triplet energy of the hostof the dark blue emitting layer which is the third emitting layer (EML)124 as much as 0.01 eV to 0.4 eV, whereby blue efficiency may be moreimproved. Although the dark blue emitting layer has been describedexemplarily, the TTA and the delayed fluorescence are applied to all theembodiments of the present invention to improve efficiency of the darkblue emitting layer or the blue emitting layer.

In all the embodiments of the present invention, the structure of thecharge generating layer (CGL) has been optimized. Although the structureof the charge generating layer (CGL) is described in the first andsecond embodiments of the present invention, the structure will beapplied to the third to sixth embodiments of the present invention. Aspreviously described, the charge generating layer includes an N typecharge generating layer and a P type charge generating layer.

The N type charge generating layer (N-CGL) may be formed of, but is notlimited to, an organic layer doped with alkali metal such as Li, Na, Kor Cs or alkali earth metal such as Mg, Ca, Sr, Ba or Ra. The alkalimetal or the alkali earth metal may be doped in the range of 0.6% ormore and 2.0% or less.

The P type charge generating layer (P-CGL) may be formed of, but is notlimited to, at least one organic host and at least one organic dopant.At least one P host may include either the same material as that of thesecond hole transporting layer (HTL) 122 which is the hole transportinglayer (HTL) adjacent thereto or a material different from that of thehole transporting layer (HTL). The triplet energy of the holetransporting layer (HTL) is 2.5 eV or more, and in this range, mayprevent electrons from being moved and prevent the triplet excitons frombeing diffused. Also, a HOMO (highest occupied molecular orbital) levelof the P host is adjusted to be proximate to a HOMO level of the secondhole transporting layer (HTL) 122, whereby injection of the holes to theemitting layer may be made. Moreover, the triplet excitons of thephosphorescence emitting layer of the second emission portion may beprevented from being diffused into the second hole transporting layer(HTL) 122, whereby a lifetime of the organic light emitting diode may beimproved. For example, the HOMO level of the P host may be in the rangeof 4.5 eV to 6.0 eV, and a LUMO (lowest unoccupied molecular orbital)level of the P dopant may be in the range of 4.5 eV to 6.0 eV. The Ptype charge generating layer (P-CGL) may have a thickness in the rangeof 5 nm to 20 nm.

In the organic light emitting display device that includes the organiclight emitting diode according to the first and second embodiments ofthe present invention, at least one among gate lines and data lineswhich define each pixel area, and a power line in parallel extended fromany one among the gate lines and the data lines are arranged on asubstrate, and a switching thin film transistor connected to the gateand data lines and a driving thin film transistor connected to theswitching thin film transistor are arranged in each pixel area. Thedriving thin film transistor is connected to the first electrode 102.

The structure of the present invention is suggested through a contourmap through optical simulation based on the organic light emitting diodeshown in FIG. 2.

FIG. 3 is a diagram illustrating a contour map according to the firstembodiment of the present invention, and FIG. 4 is a diagramillustrating a contour map according to the second embodiment of thepresent invention.

In FIGS. 3 and 4, a horizontal axis represents a wavelength, and avertical axis represents a thickness of an organic material. Although aunit of the thickness of the organic material is nanometer (nm) in FIGS.3 and 4. The thickness of the organic material indicates the thicknessof the organic layers arranged between the first electrode and thesecond electrode. The organic layers indicate organic layersconstituting the first emission portion 110 and the second emissionportion 120 as shown in FIG. 2, and include a hole transporting layer(HTL), an electron transporting layer (ETL), a charge generating layer(CGL), and an emitting layer (EML). If a buffer layer is furtherprovided below the second electrode, the buffer layer is not included inthe organic layers.

The organic light emitting diode shown in FIG. 2 is applied to the firstembodiment of the present invention, and the thickness of the organiclayers between the first electrode and the second electrode is in therange of 200 nm to 230 nm. The organic light emitting diode shown inFIG. 2 is applied to the second embodiment of the present invention, andthe thickness of the organic layers between the first electrode and thesecond electrode is in the range of 320 nm to 350 nm.

As shown in FIG. 3, it is noted from the first embodiment of the presentinvention that the thickness of the organic layers between the firstelectrode and the second electrode is in the range of 200 nm to 230 nm.For example, the thickness of the organic layers between the firstelectrode and the second electrode may be adjusted to 215 nm. And, thethickness of the first electrode 102 may be in the range of 10 nm to 15nm. The thickness of the second electrode 104 may be in the range of 100nm to 1500 Å, for example, the thickness of the second electrode 104 maybe 140 nm.

The location 114E of the first emitting layer (EML) of the firstemission portion is in the range of 30 nm to 60 nm from the firstelectrode 102. For example, the location 114E of the first emittinglayer (EML) may be at 50 nm from the first electrode 102. The location115E of the second emitting layer (EML) is in the range of 50 nm to 90nm from the first electrode 102. For example, the location 115E of thesecond emitting layer (EML) may be at 60 nm from the first electrode102. The thickness of the first emitting layer (EML) 114 may be in therange of 20 nm to 300 Å, and the thickness of the second emitting layer(EML) 115 may be in the range of 5 nm to 10 nm.

The location 124E of the third emitting layer (EML) of the secondemission portion is in the range of 120 nm to 160 nm from the firstelectrode 102. For example, the location 124E of the third emittinglayer (EML) may be at 140 nm from the first electrode 102. The thicknessof the third emitting layer (EML) 124 may be in the range of 20 nm to 30nm.

As shown in FIG. 4, it is noted from the second embodiment of thepresent invention that the thickness of the organic layers between thefirst electrode 102 and the second electrode 104 is in the range of 320nm to 350 nm. For example, the thickness of the organic layers betweenthe first electrode 102 and the second electrode 104 may be set to 340nm. And, the thickness of the first electrode 102 may be in the range of10 nm to 15 nm. The thickness of the second electrode 104 may be in therange of 100 nm to 1500 Å, for example, the thickness of the secondelectrode 104 may be 140 nm.

The location 114E of the first emitting layer (EML) of the firstemission portion is in the range of 30 nm to 60 nm from the firstelectrode 102. For example, the location 114E of the first emittinglayer (EML) may be at 40 nm from the first electrode 102. The location115E of the second emitting layer (EML) is in the range of 50 nm to 90nm from the first electrode 102. For example, the location 115E of thesecond emitting layer (EML) may be at 60 nm from the first electrode102. The thickness of the first emitting layer (EML) 114 may be in therange of 20 nm to 300 Å, and the thickness of the second emitting layer(EML) 115 may be in the range of 5 nm to 10 nm.

The location 124E of the third emitting layer (EML) of the secondemission portion is in the range of 120 nm to 160 nm from the firstelectrode 102. For example, the location 124E of the third emittinglayer (EML) may be at 140 nm from the first electrode 102. The thicknessof the third emitting layer (EML) 124 may be in the range of 20 nm to 30nm.

The results of efficiency, a color coordinate, a DCI area ratio, a DCIcoverage, and Δu′v′, which are measured in accordance with the first andsecond embodiments of the present invention, will be described withreference to Table 1.

TABLE 1 Embodiments First Embodiment Second Embodiment Efficiency (cd/A)R 6.2 5.4 G 27.0 28.6 B 2.5 2.6 W 66.7 66.5 Panel 24.6 21.1 Colorcoordinate Wx 0.314 0.302 Wy 0.353 0.364 DCI area ratio (%) 103.2 104.8DCI coverage (%) 99.6 99.7 Δu′v′ 0.029 0.021

In Table 1, referring to efficiency, it is noted that red (R) efficiencyof the first embodiment was more improved than red (R) efficiency of thesecond embodiment as much as 15%. Also, it is noted that the firstembodiment is similar to the second embodiment in green (G) efficiency,blue (B) efficiency and white (W) efficiency. It is noted that panelefficiency of the second embodiment was more improved than panelefficiency of the first embodiment as much as 16%. Therefore, it isnoted that the second embodiment was more improved than the firstembodiment in view of red efficiency and panel efficiency.

Referring to a white color coordinate (Wx, Wy), it is noted that thefirst embodiment shows (0.314, 0.353) and the second embodiment shows(0.302, 0.364).

Referring to a DCI (Digital Cinema Initiatives) area ratio, it is notedthat the first embodiment shows 103.2% and the second embodiment shows104.8%. Referring to a DCI coverage, it is noted that the firstembodiment shows 99.6% and the second embodiment shows 99.7%. As aresult, it is noted that the first embodiment and the second embodimentare similar to each other in a color reproduction ratio.

Referring to a Δu′v′ based on a viewing angle, it is noted that thefirst embodiment shows 0.029 and the second embodiment shows 0.021.Since a Δu′v′ of the second embodiment is smaller than a Δu′v′ of thefirst embodiment, it is noted that the second embodiment has color shiftrate properties more excellent than those of the first embodiment. TheΔu′v′ based on a viewing angle will be described later in detail withreference to FIG. 10.

FIG. 5 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a third example embodiment of the presentinvention.

The organic light emitting diode 200 shown in FIG. 5 includes first andsecond electrodes 202 and 204 on a substrate 201, and first and secondemission portions 210 and 220 between the first electrode 202 and thesecond electrode 204.

In the third embodiment of the present invention, the first emissionportion includes two emitting layers, and the second emission portionincludes a single emitting layer. The two emitting layers in the firstemission portion include a green emitting layer and a red emittinglayer, and the single emitting layer in the second emission portionincludes a deep blue emitting layer.

The first emission portion 210 may include a first hole transportinglayer (HTL) 212, a first emitting layer (EML) 214, a second emittinglayer (EML) 215, and a first electron transporting layer (ETL) 216.

The first emitting layer (EML) 214 constituting the first emissionportion 210 includes a red emitting layer, and the second emitting layer(EML) 215 includes a green emitting layer. The red emitting layer may becloser to the first electrode 202 than the green emitting layer.

The first emitting layer (EML) 214 of the first emission portion 210includes a red emitting layer to which a red dopant of which maximumwavelength of a PL peak is 620 nm is applied. And, the second emittinglayer (EML) 215 includes a green emitting layer to which a green dopantof which maximum wavelength of a PL peak is 532 nm is applied.

The second emission portion 220 may include a second hole transportinglayer (HTL) 222, a third emitting layer (EML) 224, and a second electrontransporting layer (ETL) 226.

The third emitting layer (EML) 224 of the second emission portion 220includes a dark blue emitting layer. The third emitting layer (EML) 224of the second emission portion 220 includes a dark blue emitting layerto which a dark blue dopant of which maximum wavelength of a PL peak is444 nm is applied.

A charge generating layer (CGL) 240 may further be provided between thefirst emission portion 210 and the second emission portion 220.

To improve blue efficiency, a triplet energy of the second holetransporting layer (HTL) 222 and the second electron transporting layer(ETL) 226 may be adjusted to be higher than a triplet energy of a hostof the dark blue emitting layer which is the third emitting layer (EML)224 as much as 0.01 eV to 0.4 eV.

Since the other elements of the third embodiment are the same as thoseof the first embodiment, their description will be omitted.

In the organic light emitting display device that includes the organiclight emitting diode according to the third embodiment of the presentinvention, at least one among gate lines and data lines which defineeach pixel area, and a power line in parallel extended from any oneamong the gate lines and the data lines are arranged on a substrate, anda switching thin film transistor connected to the gate and data linesand a driving thin film transistor connected to the switching thin filmtransistor are arranged in each pixel area. The driving thin filmtransistor is connected to the first electrode 202.

FIG. 6 suggests a structure of the present invention through a contourmap through optical simulation based on the organic light emitting diodeshown in FIG. 5.

FIG. 6 is a diagram illustrating a contour map according to the thirdembodiment of the present invention.

In FIG. 6, a horizontal axis represents a wavelength, and a verticalaxis represents a thickness of an organic material. Although a unit ofthe thickness of the organic material is nanometer (nm) in FIG. 6. Thethickness of the organic material indicates the thickness of the organiclayers arranged between the first electrode and the second electrode.The organic layers indicates organic layers constituting the firstemission portion 210 and the second emission portion 220 as shown inFIG. 5, and include a hole transporting layer (HTL), an electrontransporting layer (ETL), a charge generating layer (CGL), and anemitting layer (EML). If a buffer layer is further provided below thesecond electrode, the buffer layer is not included in the organiclayers.

As shown in FIG. 6, it is noted from the third embodiment of the presentinvention that the thickness of the organic layers between the firstelectrode 202 and the second electrode 204 is in the range of 200 nm to230 nm. For example, the thickness of the organic layers between thefirst electrode 202 and the second electrode 204 may be adjusted to 215nm. And, the thickness of the first electrode 202 may be in the range of10 nm to 15 nm.

The thickness of the second electrode 204 may be in the range of 100 nmto 1500 Å, for example, the thickness of the second electrode 204 may be140 nm.

The location 214E of the first emitting layer (EML) of the firstemission portion is in the range of 20 nm to 50 nm from the firstelectrode 202. For example, the location 214E of the first emittinglayer (EML) may be at 30 nm from the first electrode 202. The location215E of the second emitting layer (EML) is in the range of 25 nm to 60nm from the first electrode 202. For example, the location 215E of thesecond emitting layer (EML) may be at 50 nm from the first electrode202. The thickness of the first emitting layer (EML) 214 may be in therange of 5 nm to 100 Å, and the thickness of the second emitting layer(EML) 215 may be in the range of 20 nm to 30 nm.

The location 224E of the third emitting layer (EML) of the secondemission portion is in the range of 120 nm to 160 nm from the firstelectrode 202. For example, the location 224E of the third emittinglayer (EML) may be at 140 nm from the first electrode 202. The thicknessof the third emitting layer (EML) 224 may be in the range of 20 nm to 30nm.

The results of efficiency, a color coordinate, a DCI area ratio, a DCIcoverage, and a Δu′v′, which are measured in accordance with the thirdembodiment of the present invention, will be described with reference toTable 2.

TABLE 2 Embodiment Third Embodiment Efficiency (cd/A) R 5.5 G 26.9 B 2.5W 65.4 Panel 22.8 Color coordinate Wx 0.306 Wy 0.353 DCI area ratio (%)102.3 DCI coverage (%) 99.4 Δu′v′ 0.030

Although Table 2 shows the results of the third embodiment, the resultsof the third embodiment will be described as compared with Table 1corresponding to the results of the first embodiment. That is, becausethe first emitting layer and the second emitting layer, which areincluded in the first emission portion, are provided differently fromeach other in the first and the third embodiments, the results of thethird embodiment will be described as compared with the results of thefirst embodiment.

Referring to efficiency, it is noted that red (R) efficiency of thethird embodiment was reduced as much as 13% as compared with red (R)efficiency of the first embodiment. Also, it is noted that the firstembodiment is similar to the third embodiment in green (G) efficiency,blue (B) efficiency and white (W) efficiency. It is noted that panelefficiency of the third embodiment was reduced as much as 8% as comparedwith panel efficiency of the first embodiment. Therefore, it is notedthat red efficiency and panel efficiency of the third embodiment wasreduced as compared with those of the first embodiment.

Referring to a white color coordinate (Wx, Wy), it is noted that thethird embodiment shows (0.306, 0.353).

Referring to a DCI (Digital Cinema Initiatives) area ratio, it is notedthat the third embodiment shows 102.3% similar to that of the firstsecond embodiment. Referring to a DCI coverage, it is noted that thethird embodiment shows 99.4% similar to that of the first embodiment. Asa result, it is noted that the first embodiment and the third embodimentare similar to each other in a color reproduction ratio.

Referring to Δu′v′ based on a viewing angle, it is noted that the thirdembodiment shows 0.030 similar to that of the first embodiment. TheΔu′v′ based on a viewing angle will be described later in detail withreference to FIG. 10.

FIG. 7 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to a fourth example embodiment of the presentinvention.

The organic light emitting diode 300 shown in FIG. 7 includes first andsecond electrodes 302 and 304 on a substrate 301, and first and secondemission portions 310 and 320 between the first electrode 302 and thesecond electrode 304.

In the fourth embodiment of the present invention, the first emissionportion includes a single emitting layer, and the second emissionportion includes two emitting layers. The single emitting layer in thefirst emission portion includes a blue emitting layer, and the twoemitting layers in the second emission portion include a green emittinglayer and a blue emitting layer.

The first emission portion 310 may include a first hole transportinglayer (HTL) 312, a first emitting layer (EML) 314, and a first electrontransporting layer (ETL) 316.

The first emitting layer (EML) 314 constituting the first emissionportion 310 includes a dark blue emitting layer to which a dark bluedopant of which maximum wavelength of a PL peak is 444 nm is applied.

The second emission portion 320 may include a second hole transportinglayer (HTL) 322, a second emitting layer (EML) 324, a third emittinglayer (EML) 325, and a second electron transporting layer (ETL) 326.

The second emitting layer (EML) 324 of the second emission portion 320includes a green emitting layer to which a green dopant of which maximumwavelength of a PL peak is 532 nm is applied. Also, the third emittinglayer (EML) 325 includes a red emitting layer to which a red dopant ofwhich maximum wavelength of a PL peak is 620 nm is applied. The redemitting layer may be comprised to be closer to the second electrode 304than the green emitting layer.

A charge generating layer (CGL) 340 may further be provided between thefirst emission portion 310 and the second emission portion 320.

To improve blue efficiency, a triplet energy of the first holetransporting layer (HTL) 312 and the first electron transporting layer(ETL) 316 may be adjusted to be higher than a triplet energy of a hostof the dark blue emitting layer which is the first emitting layer (EML)314 as much as 0.01 eV to 0.4 eV.

Since the other elements of the fourth embodiment are the same as thoseof the first embodiment, their description will be omitted.

In the organic light emitting display device that includes the organiclight emitting diode according to the fourth embodiment of the presentinvention, at least among gate lines and data lines which define eachpixel area, and a power line in parallel extended from any one among thegate lines and the data lines are arranged on a substrate, and aswitching thin film transistor connected to the gate and data lines anda driving thin film transistor connected to the switching thin filmtransistor are arranged in each pixel area. The driving thin filmtransistor is connected to the first electrode 302.

FIG. 8 suggests a structure of the present invention through a contourmap through optical simulation based on the organic light emitting diodeshown in FIG. 7.

FIG. 8 is a diagram illustrating a contour map according to the fourthembodiment of the present invention.

In FIG. 8, a horizontal axis represents a wavelength, and a verticalaxis represents a thickness of an organic material. Although a unit ofthe thickness of the organic material is nanometer (nm) in FIG. 8. Thethickness of the organic material indicates the thickness of the organiclayers arranged between the first electrode and the second electrode.The organic layers indicates organic layers constituting the firstemission portion 310 and the second emission portion 320 as shown inFIG. 7, and include a hole transporting layer (HTL), an electrontransporting layer (ETL), a charge generating layer (CGL), and anemitting layer (EML). If a buffer layer is further provided below thesecond electrode, the buffer layer is not included in the organiclayers.

As shown in FIG. 8, it is noted from the fourth embodiment of thepresent invention that the thickness of the organic layers between thefirst electrode 302 and the second electrode 304 is in the range of 320nm to 350 nm. For example, the thickness of the organic layers arrangedbetween the first electrode 302 and the second electrode 304 may be setto 340 nm. And, the thickness of the first electrode 302 may be in therange of 10 nm to 15 nm. The thickness of the second electrode 304 maybe in the range of 100 nm to 1500 Å, for example, the thickness of thesecond electrode 304 may be 140 nm.

The location 314E of the first emitting layer (EML) of the firstemission portion is in the range of 120 nm to 160 nm from the firstelectrode 302. For example, the location 314E of the first emittinglayer (EML) may be at 140 nm from the first electrode 302. The thicknessof the first emitting layer (EML) 314 may be in the range of 20 nm to 30nm.

The location 324E of the second emitting layer (EML) of the secondemission portion is in the range of 170 nm to 200 nm from the firstelectrode 302. For example, the location 324E of the second emittinglayer (EML) may be at 190 nm from the first electrode 302. The location325E of the third emitting layer (EML) is in the range of 200 nm to 230nm from the first electrode 302. For example, the location 325E of thethird emitting layer (EML) may be at 210 nm from the first electrode302. The thickness of the second emitting layer (EML) 324 may be in therange of 20 nm to 300 Å, and the thickness of the third emitting layer(EML) 325 may be in the range of 5 nm to 10 nm.

The results of efficiency, a color coordinate, a DCI area ratio, a DCIcoverage, and a Δu′v′, which are measured in accordance with the fourthembodiment of the present invention, will be described with reference toTable 3.

TABLE 3 Embodiment Fourth Embodiment Efficiency (cd/A) R 4.3 G 27.8 B2.5 W 63.0 Panel 18.1 Color coordinate Wx 0.290 Wy 0.361 DCI area ratio(%) 103.7 DCI coverage (%) 99.6 Δu′v′ 0.028

Although Table 3 shows the results of the fourth embodiment, the resultsof the fourth embodiment will be described as compared with Table 1corresponding to the results of the first embodiment. That is, becausethe first emitting layer and the second emitting layer, which areincluded in the first emission portion, are provided differently fromeach other in the first and the fourth embodiments, the results of thefourth embodiment will be described as compared with the results of thefirst embodiment.

Referring to efficiency, it is noted that red (R) efficiency of thefourth embodiment was reduced as much as 30% as compared with red (R)efficiency of the first embodiment. Also, it is noted that the firstembodiment is similar to the fourth embodiment in green (G) efficiency,blue (B) efficiency and white (W) efficiency. It is noted that panelefficiency of the fourth embodiment was reduced as much as 6% ascompared with panel efficiency of the first embodiment. Therefore, it isnoted that red efficiency and panel efficiency of the fourth embodimentwas reduced as compared with those of the first embodiment.

Referring to a white color coordinate (Wx, Wy), it is noted that thefourth embodiment shows (0.290, 0.361).

Referring to a DCI (Digital Cinema Initiatives) area ratio, it is notedthat the fourth embodiment shows 103.7% similar to that of the firstembodiment. Referring to a DCI coverage, it is noted that the fourthembodiment shows 99.6% similar to that of the first embodiment. As aresult, it is noted that the first embodiment and the fourth embodimentare similar to each other in a color reproduction ratio.

Referring to a Δu′v′ based on a viewing angle, it is noted that thefourth embodiment shows 0.028 similar to that of the first embodiment.The Δu′v′ based on a viewing angle will be described later in detailwith reference to FIG. 10.

FIG. 9 is a diagram illustrating EL spectrum of an organic lightemitting display device according to the first to fourth embodiments ofthe present invention. In FIG. 9, a horizontal axis represents awavelength (nm) of light, and a vertical axis representselectroluminescence intensity. Electroluminescence intensity (a.u.,arbitrary unit) is a numeric value expressed as a relative value basedon a maximum value of EL spectrum. For example, as shown in FIG. 6, theelectroluminescence intensity in the blue area having a range of 440 nmto 480 nm may be 0.30 (a.u.) and the electroluminescence intensity inthe yellow-green area having a range of 540 nm to 580 nm may be 0.18(a.u.) by conversion based on 0.30 (a.u.) which is a maximum value ofthe EL spectrum. That is, 0.18 (a.u.) is expressed as a relative valuebased on 0.30 (a.u.) which is the maximum value of the EL spectrum.Also, the electroluminescence intensity in the yellow-green area isexpressed based on the electroluminescence intensity in the blue areawhich is the maximum value of EL spectrum.

Also, in FIG. 9, since the first, second, third and fourth embodimentsof the present invention are the same as those described above, theirdescription will be omitted. The EL spectrum according to the firstembodiment of the present invention is marked with a solid line, the ELspectrum according to the second embodiment is marked with a dottedline, the EL spectrum according to the third embodiment is marked withan alternate long and short dash line, and the EL spectrum according tothe fourth embodiment is marked with an alternate long and two shortdashes line.

As shown in FIG. 9, it is noted from the first to fourth embodiments ofthe present invention that three EL peaks are generated in the ELspectrum. That is, the first peak corresponds to a blue area, and awavelength corresponding to the blue area may be in the range of 440 nmto 480 nm. The second peak corresponds to a green area, and a wavelengthcorresponding to the green area may be in the range of 530 nm to 580 nm.The third peak corresponds to a red area, and a wavelength correspondingto the red area may be in the range of 600 nm to 650 nm. Therefore, itis noted that three EL peaks may have wavelengths in the range of 440 nmto 480 nm, 530 nm to 580 nm, and 600 nm to 650 nm, respectively.

In the wavelength area of the first peak, it is noted that EL intensityof the first embodiment is similar to EL intensity of each of the secondto fourth embodiments. In the wavelength area of the second peak, it isnoted that EL intensity of each of the second and fourth embodiments wasimproved as compared with each of the first and third embodiments.Therefore, it is noted that green efficiency of the second and fourthembodiments was improved as compared with the first and thirdembodiments. In the wavelength area of the third peak, it is noted thatred efficiency of the first embodiment was improved as compared with thesecond to fourth embodiments.

FIG. 10 is a diagram illustrating a Δu′v′ based on a viewing angle ofthe organic light emitting display device according to the first tofourth embodiments of the present invention. In FIG. 10, a horizontalaxis represents viewing angles, and a vertical axis represents a Δu′v′.

In FIG. 10, Δu′v′ is measured by tilting at 0°, 15°, 30°, 45° and 60°from the front of the organic light emitting display device. The Δu′v′in a specific viewing angle denotes a difference between the color shiftrate in the viewing angle 0° and the color shift rate in the specificviewing angle. For example, the Δu′v′ in the viewing angle 60° denotes adifference between the color shift rate in the viewing angle 0° and thecolor shift rate of the viewing angle 60°. The viewing angle 60° may bean angle in a side direction of the organic light emitting displaydevice. And the Δu′v′ is measured by CIE 1976 UCS diagram (u′ v′coordinate system).

Also, in FIG. 10, since the first, second, third and fourth embodimentsare the same as those described above, their description will beomitted. The variance according to the first embodiment of the presentinvention is marked with a solid line, the variance according to thesecond embodiment is marked with a dotted line, the variance accordingto the third embodiment is marked with an alternate long and short dashline, and the variance according to the fourth embodiment is marked withan alternate long and two short dashes line.

As shown in FIG. 10, it is noted that the Δu′v′ in the second embodimentis lower than that in each of the first, third and fourth embodiments ina viewing angle direction of 0° to 60° corresponding to the front sideof the organic light emitting display device. As a result, it is notedthat the color shift rate property in the second embodiment is moreexcellent than that in each of the first, third and fourth embodiments.

FIG. 11 is a brief cross-sectional diagram illustrating an organic lightemitting diode according to fifth and sixth example embodiments of thepresent invention.

The organic light emitting diode 400 shown in FIG. 11 includes first andsecond electrodes 402 and 404 on a substrate 401, and first and secondemission portions 410 and 420 between the first electrode 402 and thesecond electrode 404.

In the fifth and sixth embodiments of the present invention, the firstemission portion includes two emitting layers, and the second emissionportion includes a single emitting layer. The two emitting layers in thefirst emission portion include a yellow-green emitting layer and a redemitting layer, and the single emitting layer in the second emissionportion includes a blue emitting layer.

The first emission portion 410 may include a first hole transportinglayer (HTL) 412, a first emitting layer (EML) 414, a second emittinglayer (EML) 415, and a first electron transporting layer (ETL) 416.

The first emitting layer (EML) 414 constituting the first emissionportion 410 includes a yellow-green emitting layer to which ayellow-green dopant of which maximum wavelength of a PL peak is 556 nmis applied. The second emitting layer (EML) 415 includes a red emittinglayer to which a red dopant of which maximum wavelength of a PL peak is620 nm is applied. The yellow-green emitting layer may be closer to thefirst electrode 402 than the red emitting layer.

The second emission portion 420 may include a second hole transportinglayer (HTL) 422, a third emitting layer (EML) 424, and a second electrontransporting layer (ETL) 426.

The third emitting layer (EML) 424 of the second emission portion 420includes a blue emitting layer to which a blue dopant of which maximumwavelength of a PL peak is 456 nm is applied.

The fifth and sixth embodiments of the present invention may applyyellow-green emitting layer instead of the green emitting layer, wherebylifetime of the organic light emitting display device may be improved.

Also, a charge generating layer (CGL) 440 may further be providedbetween the first emission portion 410 and the second emission portion420.

To improve blue efficiency, a triplet energy of the second holetransporting layer (HTL) 422 and the second electron transporting layer(ETL) 426 may be adjusted to be higher than a triplet energy of a hostof the blue emitting layer which is the third emitting layer (EML) 424as much as 0.01 eV to 0.4 eV.

Since the other elements of the fourth embodiment are the same as thoseof the first embodiment, their description will be omitted.

In the organic light emitting display device that includes the organiclight emitting diode according to the fifth and sixth embodiments of thepresent invention, at least one among gate lines and data lines whichdefine each pixel area, and a power line in parallel extended from anyone among the gate lines and the data lines are arranged on a substrate,and a switching thin film transistor connected to the gate and datalines and a driving thin film transistor connected to the switching thinfilm transistor are arranged in each pixel area. The driving thin filmtransistor is connected to the first electrode 402.

The structure of the present invention is suggested through a contourmap through optical simulation based on the organic light emitting diodeshown in FIG. 11.

FIG. 12 is a diagram illustrating a contour map according to the fifthembodiment of the present invention, and FIG. 13 is a diagramillustrating a contour map according to the sixth embodiment of thepresent invention.

In FIGS. 12 and 13, a horizontal axis represents a wavelength, and avertical axis represents a thickness of an organic material. Although aunit of the thickness of the organic material is nanometer (nm) in FIGS.12 and 13. The thickness of the organic material indicates the thicknessof the organic layers arranged between the first electrode and thesecond electrode. The organic layers indicates organic layersconstituting the first emission portion 410 and the second emissionportion 420 as shown in FIG. 11, and include a hole transporting layer(HTL), an electron transporting layer (ETL), a charge generating layer(CGL), and an emitting layer (EML). If a buffer layer is furtherprovided below the second electrode, the buffer layer is not included inthe organic layers.

The organic light emitting diode shown in FIG. 11 is applied to thefifth embodiment of the present invention, and the thickness of theorganic layers arranged between the first electrode and the secondelectrode is in the range of 200 nm to 240 nm. The organic lightemitting diode shown in FIG. 11 is applied to the sixth embodiment ofthe present invention, and the thickness of the organic layers arrangedbetween the first electrode and the second electrode is in the range of340 nm to 370 nm.

As shown in FIG. 12, it is noted from the fifth embodiment of thepresent invention that the thickness of the organic layers between thefirst electrode and the second electrode is in the range of 200 nm to240 nm. For example, the thickness of the organic layers between thefirst electrode and the second electrode may be adjusted to 225 nm. And,the thickness of the first electrode 402 may be in the range of 10 nm to15 nm. The thickness of the second electrode 404 may be in the range of100 nm to 1500 Å, for example, the thickness of the second electrode 404may be 140 nm.

The location 414E of the first emitting layer (EML) of the firstemission portion is in the range of 30 nm to 60 nm from the firstelectrode 402. For example, the location 414E of the first emittinglayer (EML) may be at 50 nm from the first electrode 402. The location415E of the second emitting layer (EML) is in the range of 50 nm to 90nm from the first electrode 402. For example, the location 415E of thesecond emitting layer (EML) may be at 60 nm from the first electrode402. The thickness of the first emitting layer (EML) 414 may be in therange of 20 nm to 300 Å, and the thickness of the second emitting layer(EML) 415 may be in the range of 5 nm to 10 nm.

The location 424E of the third emitting layer (EML) of the secondemission portion is in the range of 120 nm to 160 nm from the firstelectrode 402. For example, the location 424E of the third emittinglayer (EML) may be at 140 nm from the first electrode 402. The thicknessof the third emitting layer (EML) 424 may be in the range of 20 nm to 30nm.

As shown in FIG. 13, it is noted from the sixth embodiment of thepresent invention that the thickness of the organic layers arrangedbetween the first electrode 402 and the second electrode 404 is in therange of 340 nm to 370 nm. For example, the thickness of the organiclayers between the first electrode 402 and the second electrode 404 maybe adjusted to 360 nm. And, the thickness of the first electrode 402 maybe in the range of 10 nm to 15 nm.

The thickness of the second electrode 404 may be in the range of 100 nmto 1500 Å, for example, the thickness of the second electrode 404 may be140 nm.

The location 414E of the first emitting layer (EML) of the firstemission portion is in the range of 30 nm to 60 nm from the firstelectrode 402. For example, the location 414E of the first emittinglayer (EML) may be at 40 nm from the first electrode 402. The location415E of the second emitting layer (EML) is in the range of 50 nm to 90nm from the first electrode 402. For example, the location 415E of thesecond emitting layer (EML) may be at 60 nm from the first electrode402. The thickness of the first emitting layer (EML) 414 may be in therange of 20 nm to 300 Å, and the thickness of the second emitting layer(EML) 415 may be in the range of 5 nm to 10 nm.

The location 424E of the third emitting layer (EML) of the secondemission portion is in the range of 120 nm to 160 nm from the firstelectrode 402. For example, the location 424E of the third emittinglayer (EML) may be at 140 nm from the first electrode 402. The thicknessof the third emitting layer (EML) 424 may be in the range of 20 nm to 30nm.

The results of efficiency, a color coordinate, a DCI area ratio, a DCIcoverage, and a Δu′v′, which are measured in accordance with the fifthand sixth embodiments of the present invention, will be described withreference to Table 4.

TABLE 4 Embodiment Fifth Embodiment Sixth Embodiment Efficiency (cd/A) R8.1 6.6 G 21.0 19.0 B 2.8 2.6 W 63.1 57.1 Panel 22.4 20.3 Colorcoordinate Wx 0.336 0.333 Wy 0.325 0.328 DCI area ratio (%) 97.3 94.7DCI coverage (%) 96.4 93.7 Δu′v′ 0.033 0.029

In Table 4, referring to efficiency, it is noted that red (R) efficiencyof the fifth embodiment was more improved than red (R) efficiency of thesixth embodiment as much as 20% and green (G) efficiency of the fifthembodiment was more improved than green (G) efficiency of the sixthembodiment as much as 10%. Also, it is noted that blue (B) efficiency ofthe fifth embodiment was more improved than blue (B) efficiency of thesixth embodiment as much as 8% and white (W) efficiency of the fifthembodiment was more improved than white (W) efficiency of the sixthembodiment as much as 10%. It is noted that panel efficiency of thefifth embodiment was more improved than panel efficiency of the sixthembodiment as much as 10%. Therefore, it is noted that the fifthembodiment was more improved than the sixth embodiment in view of redefficiency, green efficiency, blue efficiency, white efficiency andpanel efficiency.

Referring to a white color coordinate (Wx, Wy), it is noted that thefifth embodiment shows (0.336, 0.325) and the sixth embodiment shows(0.333, 0.328).

Referring to a DCI (Digital Cinema Initiatives) area ratio, it is notedthat the fifth embodiment shows 97.3% and the sixth embodiment shows94.7%. Referring to a DCI coverage, it is noted that the fifthembodiment shows 96.4% and the sixth embodiment shows 93.7%. As aresult, it is noted that a color reproduction ratio of the fifthembodiment is more excellent than that of the sixth embodiment.

Referring to a Δu′v′ based on a viewing angle, it is noted that thefifth embodiment shows 0.033 and the sixth embodiment shows 0.029. Sincethe Δu′v′ of the sixth embodiment is smaller than Δu′v′ of the fifthembodiment, it is noted that the sixth embodiment has color shift rateproperties more excellent than color shift rate properties of the fifthembodiment. The Δu′v′ based on a viewing angle will be described laterin detail with reference to FIG. 15.

FIG. 14 is a diagram illustrating EL spectrum of an organic lightemitting display device according to the fifth and sixth embodiments ofthe present invention. In FIG. 14, a horizontal axis represents awavelength of light, and a vertical axis represents electroluminescenceintensity. Electroluminescence intensity is a numeric value expressed asa relative value based on a maximum value of EL spectrum.

Also, in FIG. 14, since the fifth and sixth embodiments are the same asthose described above, their description will be omitted. The ELspectrum according to the fifth embodiment of the present invention ismarked with a solid line, and the EL spectrum according to the sixthembodiment is marked with a dotted line.

As shown in FIG. 14, it is noted from the fifth and sixth embodiments ofthe present invention that three EL peaks are generated in the ELspectrum. That is, the first peak corresponds to a blue area, and awavelength corresponding to the blue area may be in the range of 440 nmto 480 nm. The second peak corresponds to a green area, and a wavelengthcorresponding to the green area may be in the range of 530 nm to 580 nm.The third peak corresponds to a red area, and a wavelength correspondingto the red area may be in the range of 600 nm to 650 nm. Therefore, itis noted that three EL peaks may have wavelengths in the range of 440 nmto 480 nm, 530 nm to 580 nm, and 600 nm to 650 nm, respectively.

In the wavelength area of the first peak, it is noted that EL intensityof the fifth embodiment is similar to EL intensity of the sixthembodiment. In the wavelength area of the second peak, it is noted thatEL intensity of the fifth embodiment was improved as compared with ELintensity of the sixth embodiment. Therefore, it is noted that greenefficiency of the fifth embodiment was improved as compared with thesixth embodiment. In the wavelength area of the third peak, it is notedthat red efficiency of the fifth embodiment was improved as comparedwith the sixth embodiment.

FIG. 15 is a diagram illustrating a Δu′v′ based on a viewing angle ofthe organic light emitting display device according to the fifth andsixth embodiments of the present invention. In FIG. 15, a horizontalaxis represents viewing angles, and a vertical axis represents a Δu′v′.

In FIG. 15, the Δu′v′ is measured by tilting at 0°, 15°, 30°, 45° and60° from the front of the organic light emitting display device.

Also, in FIG. 15, since the fifth and sixth embodiments are the same asthose described above, their description will be omitted. The varianceaccording to the fifth embodiment is marked with a solid line, and thevariance according to the sixth embodiment is marked with a dotted line.

As shown in FIG. 15, it is noted that the Δu′v′ in the sixth embodimentis lower than that in the fifth embodiment in a viewing angle directionof 0° to 60° corresponding to the front side of the organic lightemitting display device. As a result, it is noted that the color shiftrate property in the sixth embodiment is more excellent than that in thefifth embodiment.

It is noted that the organic light emitting display device based on thetop emission type according to the first to sixth embodiments has anaperture ratio more improved as much as 40% or more than that of theorganic light emitting display device based on the bottom emission type.Also, since the polarizer is not required, luminance of the organiclight emitting display device may be improved. Therefore, the organiclight emitting display device having an improved aperture ratio,improved luminance, improved efficiency, and an improved colorreproduction ratio may be provided.

The organic light emitting diode according to the present inventiondescribed as above may be applied to a lighting device, may be used as athin light source of an LCD device, or may be applied to a displaydevice. Hereinafter, the embodiment of the organic light emitting diodeaccording to the present invention, which is applied to the displaydevice, will be described.

FIG. 16 is a cross-sectional diagram illustrating an organic lightemitting display device, which includes an organic light emitting diodeaccording to an example embodiment of the present invention, wherein theorganic light emitting display device is based on the aforementionedorganic light emitting diode according to the first to sixth embodimentsof the present invention.

As shown in FIG. 16, the organic light emitting display device 1000 ofthe present invention includes a substrate 501, a thin film transistorTFT, a first electrode 502, an emission portion 1180, and a secondelectrode 502. The thin film transistor TFT includes a gate electrode1115, a gate insulating layer 1120, a semiconductor layer 1131, a sourceelectrode 1133, and a drain electrode 1135.

Although the thin film transistor TFT is shown in an inverted staggeredstructure, the thin film transistor TFT may be formed in a coplanarstructure.

The substrate 501 may be formed of glass, metal or plastic.

The gate electrode 1115 is formed on the substrate 501, and is connectedwith a gate line (not shown). The gate electrode 1115 may be amulti-layer of any one among Mo, Al, Cr, Δu, Ti, Ni, Nd, and Cu, ortheir alloy.

The gate insulating layer 1120 is formed on the gate electrode 1115, andmay be, but is not limited to, a silicon oxide (SiOx) film, a siliconnitride (SiNx) film or a multi-layer of SiOx and SiNx.

The semiconductor layer 1131 is formed on the gate insulating layer1120, and may be formed of amorphous silicon (a-Si), polycrystallinesilicon (poly-Si), oxide semiconductor or organic semiconductor. If thesemiconductor layer 1131 is formed of an oxide semiconductor, thesemiconductor layer 1131 may be formed of, but is not limited to, ITO(Indium Tin Oxide), IZO (Indium Zinc Oxide), or ITZO (Indium Tin ZincOxide). Although an etch stopper (not shown) may be formed on thesemiconductor layer 1131 to protect the semiconductor layer 1131, theetch stopper may be omitted depending on the structure of the thin filmtransistor (TFT).

The source electrode 1133 and the drain electrode 1135 may be formed onthe semiconductor layer 1131. The source electrode 1133 and the drainelectrode 1135 may include a single layer or multi-layer comprised ofany one among Mo, Al, Cr, Δu, Ti, Ni, Nd and Cu and their alloy.

A passivation layer 1140 is formed on the source electrode 1133 and thedrain electrode 1135, and may be formed of a silicon oxide (SiOx) film,a silicon nitride (SiNx) film, or a multi-layer of SiOx and SiNx.Alternatively, the passivation layer 1140 may be formed of, but is notlimited to, acrylic resin or polyimide resin.

The first electrode 502 is formed on the passivation layer 1140, and maybe formed of, but is not limited to, Δu, Ag, Al, Mo, Mg or the like, ortheir alloy. Alternatively, the first electrode 502 may be formed of,but is not limited to, ITO (indium tin oxide), IZO (indium zinc oxide),or the like. A reflective electrode is additionally provided below thefirst electrode 502 to reflect light toward the second electrode 504.

The first electrode 502 is electrically connected with the drainelectrode 1135 through a contact hole CH of a predetermined area of thepassivation layer 1140. Although the drain electrode 1135 and the firstelectrode 502 are electrically connected with each other in FIG. 16, thesource electrode 1133 and the first electrode 502 may electrically beconnected with each other through the contact hole CH of thepredetermined area of the passivation layer 1140.

A bank layer 1170 is formed on the first electrode 502, and defines apixel area. That is, the bank layer 1170 is formed in a boundary areabetween a plurality of pixels in a matrix arrangement, whereby the pixelarea is defined by the bank layer 1170. The bank layer 1170 may beformed of an organic material such as benzocyclobutene (BCB) basedresin, acrylic resin or polyimide resin. Alternatively, the bank layer1170 may be formed of a photoresist that includes a black pigment. Inthis case, the bank layer 1170 serves as a light shielding member.

The emission portion 1180 is formed on the bank layer 1170. The emissionportion 1180 includes a first emission portion and a second emissionportion, which are formed on the first electrode 502, as shown in FIGS.2, 5, 7 and 11.

The second electrode 504 is formed on the emission portion 1180, and maybe formed of, but is not limited to, ITO (indium tin oxide), IZO (indiumzinc oxide), or the like, which is a transparent conductive materialsuch as TCO (transparent conductive oxide). A buffer layer mayadditionally be provided below the second electrode 504.

An encapsulation layer 1190 is provided on the second electrode 504. Theencapsulation layer 1190 serves to prevent water from being permeatedinto the emission portion 1180. The encapsulation layer 1190 may beformed of a plurality of layers deposited with different inorganicmaterials, or may be formed of a plurality of layers alternatelydeposited with inorganic material and organic material. And, anencapsulation substrate 701 may be bonded to the first substrate 501 bythe encapsulation layer 1190. The encapsulation substrate 701 may beformed of glass or plastic, or may be formed of metal. A color filter702 and black matrixes 703 are arranged on the encapsulation substrate701. The light emitted from the emission portion 1180 advances towardthe encapsulation substrate 701 to display an image through the colorfilter 702.

As described above, according to the present invention, one among thetwo emission portions includes a green emitting layer or a yellow-greenemitting layer and a red emitting layer, whereby green efficiency andred efficiency may be improved, and the color reproduction ratio may beimproved.

Also, as one among the two emission portions includes two emittinglayers and three EL peaks are provided, efficiency and the colorreproduction ratio may be improved, whereby the organic light emittingdisplay device applicable to a large sized TV may be provided.

Also, since the polarizer is not required, the organic light emittingdisplay device having improved luminance may be provided.

Also, since the top emission type is used, the organic light emittingdisplay device having an improved aperture ratio may be provided.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic light emitting display device,comprising: first and second electrodes facing each other on asubstrate; a first emission portion on the first electrode; and a secondemission portion on the first emission portion, wherein at least oneamong the first emission portion and the second emission portionincludes two emitting layers, and the first emission portion and thesecond emission portion have emission characteristics that exhibit threeEL peaks, wherein the first emission portion includes a first holetransport layer and a first electron transport layer, and wherein thesecond emission portion includes a second hole transport layer and asecond electron transport layer.
 2. The organic light emitting displaydevice of claim 1, wherein the first emission portion includes the twoemitting layers, and the second emission portion includes a singleemitting layer.
 3. The organic light emitting display device of claim 2,wherein the two emitting layers in the first emission portion includes agreen emitting layer and a red emitting layer, and the single emittinglayer in the second emission portion includes a dark blue emittinglayer.
 4. The organic light emitting display device of claim 3, whereinthe green emitting layer is disposed in a range of 30 nm to 60 nm fromthe first electrode, the red emitting layer is disposed in a range of 50nm to 90 nm from the first electrode, and the dark blue emitting layeris disposed in a range of 120 nm to 160 nm from the first electrode. 5.The organic light emitting display device of claim 3, wherein the redemitting layer is disposed in a range of 20 nm to 50 nm from the firstelectrode, the green emitting layer is disposed in a range of 25 nm to60 nm from the first electrode, and the dark blue emitting layer isdisposed in a range of 120 nm to 160 nm from the first electrode.
 6. Theorganic light emitting display device of claim 3, wherein a maximumwavelength of a PL peak of the green emitting layer includes 532 nm, amaximum wavelength of a PL peak of the red emitting layer includes 620nm, and a maximum wavelength of a PL peak of the dark blue emittinglayer includes 444 nm.
 7. The organic light emitting display device ofclaim 2, further comprising organic layers including the first emissionportion and the second emission portion between the first electrode andthe second electrode, wherein the organic layers have a thickness in therange of 200 nm to 230 nm or the 320 nm to 350 nm.
 8. The organic lightemitting display device of claim 2, wherein the two emitting layers inthe first emission portion include a yellow-green emitting layer and ared emitting layer, and the single emitting layer in the second emissionportion includes a blue emitting layer.
 9. The organic light emittingdisplay device of claim 8, wherein the yellow-green emitting layer isdisposed in a range of 30 nm to 60 nm from the first electrode, the redemitting layer is disposed in a range of 50 nm to 90 nm from the firstelectrode, and the blue emitting layer is disposed in a range of 120 nmto 160 nm from the first electrode.
 10. The organic light emittingdisplay device of claim 8, wherein a maximum wavelength of a PL peak ofthe yellow-green emitting layer includes 556 nm, a maximum wavelength ofa PL peak of the red emitting layer includes 620 nm, and a maximumwavelength of a PL peak of the blue emitting layer includes 456 nm. 11.The organic light emitting display device of claim 8, further comprisingorganic layers including the first emission portion and the secondemission portion between the first electrode and the second electrode,wherein the organic layers have a thickness in the range of 200 nm to240 nm or the 340 nm to 370 nm.
 12. The organic light emitting displaydevice of claim 1, wherein the first emission portion includes a singleemitting layer, and the second emission portion includes two emittinglayers.
 13. The organic light emitting display device of claim 12,wherein the single emitting layer in the first emission portion includesa dark blue emitting layer, and the two emitting layers in the secondemission portion include a green emitting layer and a red emittinglayer.
 14. The organic light emitting display device of claim 12,wherein the dark blue emitting layer is disposed in a range of 120 nm to160 nm from the first electrode, the green emitting layer is disposed ina range of 170 nm to 200 nm from the first electrode, and the redemitting layer is disposed in a range of 200 nm to 230 nm from the firstelectrode.
 15. The organic light emitting display device of claim 12,wherein a maximum wavelength of a PL peak of the green emitting layerincludes 532 nm, a maximum wavelength of a PL peak of the red emittinglayer includes 620 nm, and a maximum wavelength of a PL peak of the darkblue emitting layer includes 444 nm.
 16. The organic light emittingdisplay device of claim 12, further comprising organic layers includingthe first emission portion and the second emission portion between thefirst electrode and the second electrode, wherein the organic layershave a thickness in the range of 320 nm to 350 nm.
 17. The organic lightemitting display device of claim 1, wherein each of the first electrodeand the second electrode includes one among reflective electrode andtransflective electrode.
 18. The organic light emitting display deviceof claim 1, wherein the three EL peaks have wavelengths in the ranges of440 nm to 480 nm, 530 nm to 580 nm, and 600 nm to 650 nm.
 19. Theorganic light emitting display device of claim 1, further comprising: acharge generation layer between the first emission portion and thesecond emission portion.
 20. The organic light emitting display deviceof claim 11, wherein a color change rate based on a viewing angle of theorganic light emitting display device includes less than 0.030.